This invention relates to ink-jet printer and printing method which perform printing by discharging ink from an ink-jet head onto a printing object, an auxiliary member, an ink-jet head, a warp correction method, an ink-jet head unit and color-mixture reducing method.
In recent years, there is an increasing need for liquid-crystal displays, and especially for color liquid-crystal displays, with development of personal computers, and especially handheld personal computers. However, it is necessary to reduce cost of the liquid-crystal displays so that the personal computers can be more widely used. Especially, it is required to reduce cost of the color filter which is considerably expensive. Conventionally, various methods have been practiced to meet the above requirements while satisfying the necessary characteristics of color filter, however, none of the methods satisfies all the necessary characteristics. The previous methods are as follows.
The first method is a pigment diffusion method. This method obtains a single-color pattern by forming a photosensitive resin layer where pigment is diffused on a substrate and followed by patterning of the resin layer. This process is repeated three times to form an R, G and B color filter layer.
The second method is a coloring method. This method obtains a colored pattern by coating. water-soluble polymeric material, as coloring material, on a glass substrate, forming it into a desired pattern by photolithography process, and dipping the obtained pattern into a coloring bath. This process is repeated three times to form an R, G and B color filter layer.
The third method is an electrodeposition method. This method performs electrodeposition of a first color by forming a transparent electrode into a pattern on a substrate and dipping the electrode into an electrodeposition coating liquid including pigment, resin, electrolyte and the like. This process is repeated three times to form an R, G and B color filter layer, and finally, the color filter layer is sintered.
The fourth method is a printing method. This method forms a colored layer by diffusing pigment on a heat-setting type resin by printing three times for coloring R, G and B, and heating the resin to set.
Generally, a protective layer is formed on the colored layer in any of these methods.
The above methods repeat one process three times to color the three R, G and B colors, which increases cost. Further, as the number of processes is great, the yield is lowered. Further, the electrodepdsition method, in which the formable pattern shape is limited, cannot be applied to a TFT (Thin Film Transistor) without difficulty by using the present technique. Further, the printing method with poor resolution and smoothness cannot be employed to form fine pitch patterns without difficulty.
To compensate these drawbacks, Japanese Patent Application Laid-Open Nos. 59-75205, 63-235901, and 1-217320 disclose manufacturing a color filter by using an ink-jet printing method. According to these conventional arts, ink including three R (red), G (green) and B (blue) color matters is discharged onto a light-transmitting type subject in accordance with an ink-jet method, and the respective color ink is dried to form colored image portion. The ink-jet method enables formation of R, G and B pixels in one process, thus greatly simplifies manufacturing process and greatly reduces cost.
A known ink-jet method is so-called bubble-jet method which causes film boiling by thermal energy to form a bubble and discharges ink by volume expansion of the bubble. In a case where the bubble-jet method is applied to an ink-jet head, the temperature of the ink-jet head increases due to the thermal energy. The temperature rise expands the ink-jet head, which may shift the positions of discharge nozzles for discharging ink. Recently, a long ink-jet head where a large number of nozzles are arrayed is employed, and the ink-jet head is scanned in a direction approximately orthogonal to a direction along the array of the nozzles for coloring a large number of pixel arrays at one scanning. The shift of the positions of the discharge nozzles due to expansion of the ink-jet head in its lengthwise direction is a serious problem.
Further, in the above long ink-jet head, it is difficult to manufacture a head such that a large number of nozzles, xcexcm order apart, are arrayed in one line. Especially, when high-precision ink discharging is required as in manufacturing a color filter, it is very important to improve positional precision of the nozzles.
The present invention has been made in consideration of the above situation, and has its object to provide ink-jet printer and printing method which reduce temperature rise of an ink-jet head to the utmost, an auxiliary member, an ink-jet head and a warp correction method for the ink-jet head.
Further, another object of the present invention is to provide an ink-jet printer and printing method which array nozzles of a long ink-jet head in line with high precision, an auxiliary member, an ink-jet head and a warp correction method for the ink-jet head.
According to the present invention, the foregoing object is attained by providing an ink-jet printer which performs printing by discharging ink from an ink-jet head onto a printing object, comprising: a long ink-jet head having a plurality of ink-discharge nozzles arrayed in a lengthwise direction; and a plate-shaped auxiliary member attached to said ink-jet head along the lengthwise direction, said auxiliary member having a predetermined volume to increase the thermal capacity of said ink-jet head, and having a function to correct warp of said ink-jet head, wherein said auxiliary member has a plurality of warp correction portions provided at positions corresponding to different positions in the lengthwise direction of said ink-jet head.
Further, the foregoing object is attained by providing an ink-jet printing method for performing printing by discharging ink from an ink-jet head onto a printing object, comprising the step of scanning, relatively to said printing object, a long ink-jet head in which a plurality of ink-discharge nozzles arrayed in a lengthwise direction, and to which a plate auxiliary member is attached along the lengthwise direction, while performing printing by discharging ink from said ink-jet head, said auxiliary member having a predetermined volume to increase the thermal capacity of said ink-jet head, and having a plurality of warp correction portions provided at positions corresponding to different positions in the lengthwise direction of said ink-jet head.
Further, the foregoing object is attained by providing an auxiliary member attached to a long ink-jet head in which a plurality of ink-discharge nozzles are arrayed in a lengthwise direction, wherein said auxiliary member has a predetermined volume to increase the thermal capacity of said ink-jet head, and has a plurality of warp correction portions provided at positions corresponding to different positions in the lengthwise direction of said ink-jet head so as to correct warp of said ink-jet head.
According to an aspect of the present invention, the foregoing object is attained by providing a long ink-jet head in which a plurality of ink-discharge nozzles are arrayed in a lengthwise direction, integrally comprising an auxiliary member having a predetermined volume to increase the thermal capacity of said ink-jet head, and having a plurality of warp correction portions provided at positions corresponding to different positions in the lengthwise direction of said ink-jet head, so as to correct warp of said ink-jet head.
Further, the foregoing object is attained by providing a warp correction method for correcting warp of a long ink-jet head in which a plurality of ink-discharge nozzles are arrayed in a lengthwise direction, wherein said ink-jet head has first screw holes along the lengthwise direction, while said auxiliary member has second screw holes having a larger diameter than that of said first screw holes, at positions corresponding to the first screw holes,
and wherein the warp of said ink-jet head is corrected by pulling said ink-jet head toward said auxiliary member by screw-inserting a screw which can be fit-inserted into said first screw hole via said second screw hole, while pushing said ink-jet head from said auxiliary member by screw-inserting a screw which can be fit-inserted into said second screw hole.
Further, according to another aspect of the present invention, the foregoing object is attained by providing a long ink-jet head in which a plurality of ink-discharge nozzles are arrayed in a lengthwise direction, used in a method for manufacturing a color filter by scanning said ink-jet head relatively to a coloring object while performing printing by discharging ink from said ink-jet head, wherein a pixel width GL of one pixel of said color filter, an ink dot diameter CL, a slant angle xcex8 of said ink-jet head in a direction orthogonal to a scanning direction, and a nozzle shift width y in an direction orthogonal to an ideal straight line where the plurality of ink-discharge nozzles are arrayed if said ink-jet head is not warped, are set to satisfy yxe2x89xa6(GLxe2x88x92CL)/sin xcex8 (0xc2x0 less than xcex8 less than 90xc2x0).
Further, the foregoing object is attained by providing an ink-jet head unit having a plurality of long ink-jet heads each having a plurality of ink-discharge nozzles arrayed in a lengthwise direction, used in a method for manufacturing a color filter by scanning said ink-jet head relatively to a coloring object while performing printing by discharging ink from said ink-jet head, wherein a pixel width GL of one pixel of said color filter, an ink dot diameter CL, a slant angle xcex8 of said ink-jet head in a direction orthogonal to a scanning direction, and a nozzle shift width y in an direction orthogonal to an ideal straight line where the plurality of ink-discharge nozzles are: arrayed if said ink-jet head is not warped, are set to satisfy yxe2x89xa6(GLxe2x88x92CL)/sin xcex8 (0xc2x0  less than xcex8 less than 90xc2x0).
Other objects and advantages besides those discussed above shall be apparent to those skilled in the art from the description of a preferred embodiment of the invention which follows. In the description, reference is made to accompanying drawings, which form a part thereof, and which illustrate an example of the invention. Such example, however, is not exhaustive of the various embodiments of the invention, and therefore reference is made to the claims which follow the description for determining the scope of the invention.